SUPERVISOR TO ATTACH PROCESSING LABEL HERE Figures Words STUDENT NUMBER Letter Victorian Certi cate of Education 2007 CHEMISTRY Written examination 1 Wednesday 13 June 2007 Reading time: 11.45 am to 12.00 noon (15 minutes) Writing time: 12.00 noon to 1.30 pm (1 hour 30 minutes) QUESTION AND ANSWER BOOK Structure of book Section Number of questions Number of questions to be answered Number of marks A 20 20 20 B 7 7 53 Total 73 Students are permitted to bring into the examination room: pens, pencils, highlighters, erasers, sharpeners, rulers and one scientic calculator. Students are NOT permitted to bring into the examination room: blank sheets of paper and/or white out liquid/tape. Materials supplied Question and answer book of 21 pages, with a detachable data sheet in the centrefold. Answer sheet for multiple-choice questions. Instructions Detach the data sheet from the centre of this book during reading time. Write your student number in the space provided above on this page. Check that your name and student number as printed on your answer sheet for multiple-choice questions are correct, and sign your name in the space provided to verify this. All written responses must be in English. At the end of the examination Place the answer sheet for multiple-choice questions inside the front cover of this book. Students are NOT permitted to bring mobile phones and/or any other unauthorised electronic devices into the examination room. ' VICTORIAN CURRICULUM AND ASSESSMENT AUTHORITY 2007
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SUPERVISOR TO ATTACH PROCESSING LABEL HERE
Figures
Words
STUDENT NUMBER Letter
Victorian CertiÞ cate of Education2007
CHEMISTRYWritten examination 1
Wednesday 13 June 2007 Reading time: 11.45 am to 12.00 noon (15 minutes) Writing time: 12.00 noon to 1.30 pm (1 hour 30 minutes)
QUESTION AND ANSWER BOOK
Structure of bookSection Number of
questionsNumber of questions
to be answeredNumber of
marks
A 20 20 20B 7 7 53
Total 73
� Students are permitted to bring into the examination room: pens, pencils, highlighters, erasers, sharpeners, rulers and one scientiÞ c calculator.
� Students are NOT permitted to bring into the examination room: blank sheets of paper and/or white out liquid/tape.
Materials supplied� Question and answer book of 21 pages, with a detachable data sheet in the centrefold.� Answer sheet for multiple-choice questions.
Instructions� Detach the data sheet from the centre of this book during reading time.� Write your student number in the space provided above on this page.� Check that your name and student number as printed on your answer sheet for multiple-choice
questions are correct, and sign your name in the space provided to verify this.
� All written responses must be in English.
At the end of the examination� Place the answer sheet for multiple-choice questions inside the front cover of this book.
Students are NOT permitted to bring mobile phones and/or any other unauthorised electronic devices into the examination room.
Question 1Analysis of the components of a mixture using gas-liquid chromatography normally involves measuring theA. Rf values of components, using a gas as the mobile phase.B. Rf values of components, using a liquid as the mobile phase.C. retention time of components, using a gas as the mobile phase.D. retention time of components, using a liquid as the mobile phase.
Question 2Which one of the following analyses is best performed using atomic absorption spectroscopy?A. measuring the amount of potassium in saltB. determining the amount of caffeine in coffeeC. measuring the carbonate content of mineral waterD. detecting the presence of ethanoic acid in a sample of wine
Question 3Different quantities of nitrogen oxide (NO) are listed below.Which one contains the least number of molecules?A. 6 × 102 L at 273 K and 1 atmB. 6 × 1023 moleculesC. 6 × 102 g D. 6 mol
Question 4When 2.54 g of solid iodine reacts with excess chlorine and the unreacted chlorine is evaporated, 4.67 g of a yellow product remains.The empirical formula of the product isA. ICl2B. ICl3C. ICl4D. ICl5
SECTION A � Multiple-choice questions
Instructions for Section AAnswer all questions in pencil on the answer sheet provided for multiple-choice questions.Choose the response that is correct or that best answers the question.A correct answer scores 1, an incorrect answer scores 0. Marks will not be deducted for incorrect answers. No marks will be given if more than one answer is completed for any question.
3 2007 CHEM EXAM 1
SECTION A � continuedTURN OVER
Question 5Chromatogram 1 was obtained by analysis of a sample of a mixture of two sugars, A and B, using high-performance liquid chromatography (HPLC). Chromatogram 2 was obtained by analysing another sample of the same mixture by HPLC under different conditions.
Consider the following changes which could be made to the operating conditions for HPLC.I decreasing the pressure of the mobile phaseII decreasing the temperatureIII using a less tightly packed column
Which of the changes would be most likely to produce chromatogram 2?A. I onlyB. II onlyC. III onlyD. I and II only
time (min) time (min)20
chromatogram 1 chromatogram 2
30 12 18
A
B
A
B
2007 CHEM EXAM 1 4
SECTION A � continued
Questions 6 and 7 refer to the following information.Propanone (C3H6O) can be made from 2-propanol using a copper-zinc catalyst.
C3H8O(g) C3H6O(g) + H2(g); ∆H = �54 kJ mol�1
Question 6At equilibrium at a particular temperature, 10% of the 2-propanol is converted to propanone.In order to increase the percentage yield of propanone at equilibrium, you shouldA. lower the temperature and lower the pressure.B. lower the temperature and raise the pressure.C. raise the temperature and lower the pressure.D. raise the temperature and raise the pressure.
Question 7When 2-propanol reacts to form an equilibrium mixture with propanone and hydrogen, which one of the following best represents how the rates of the forward and back reactions change over time?
Question 8A chemical reaction has a ∆H of �150 kJ mol�1 and the activation energy for its reverse reaction is 350 kJ mol�1.The activation energy, in kJ mol�1, of the forward reaction isA. +500B. +200C. +150D. �200
time
rate
time
rate
time
rate
time
rate
C3H8O(g) → C3H6O(g) + H2(g)
C3H8O(g) → C3H6O(g) + H2(g)
C3H8O(g) → C3H6O(g) + H2(g)
C3H8O(g) → C3H6O(g) + H2(g)
C3H6O(g) + H2(g) → C3H8O(g)
C3H6O(g) + H2(g) → C3H8O(g)
C3H6O(g) + H2(g) → C3H8O(g)
C3H6O(g) + H2(g) → C3H8O(g)
B.A.
C. D.
5 2007 CHEM EXAM 1
SECTION A � continuedTURN OVER
Question 9Which one of the following is least likely to be a product of a redox reaction between sulfuric acid and zinc metal?A. H2
B. H2SC. SO2
D. SO3
Question 10Cuts and wounds are often stitched using a biodegradable polymer with the formula
It is made from a condensation polymerisation reaction between lactic acid (HOCH(CH3)COOH) and glycolic acid.The formula of glycolic acid isA. HOCH2COOHB. HOCH2CH2OHC. HOOCCH2COOHD. HOOCCH2CH2OH
Question 11Which of the following statements would apply to compounds that belong to the same homologous series?
I they have similar physical propertiesII they have similar chemical propertiesIII they contain the same functional groupIV they have the same molecular formula but different structures
A. III only B. IV onlyC. II and III onlyD. I, II, III and IV
� (�CH2�C�O�CH�C�O�)n�
O CH3 O
2007 CHEM EXAM 1 6
SECTION A � continued
etheneReaction 1 Reaction 2 Reaction 3
compound X compound Y compound ZHBr NaOH CH3CH2COOH/H+
time
amount of HI (mol)
experiment 1
experiment 2
Questions 12 and 13 refer to the following information.Ethene can be converted into other carbon-containing compounds using the reagents shown in the following ß ow chart.
Question 12Compounds X, Y and Z are, respectivelyA. bromoethane, ethanol, propyl ethanoate.B. bromoethane, ethanol, ethyl propanoate.C. bromoethene, ethanoic acid, ethyl propanoate.D. bromoethene, ethene hydroxide, propyl ethanoate.
Question 13Reactions 1, 2 and 3 can be described as, respectivelyA. addition, addition, neutralisation.B. addition, substitution, condensation.C. substitution, neutralisation, oxidation.D. substitution, substitution, condensation.
Question 14 Hydrogen iodide is produced by the reaction between hydrogen and iodine.
H2(g) + I2(g) 2HI(g)
Two experiments were conducted.Experiment 1: quantities of H2(g) and I2(g) were placed in a sealed vessel and the reaction allowed to proceed at constant temperature.Experiment 2: experiment 1 was repeated, but at a different temperature.The graph below shows the amount of hydrogen iodide produced over the course of experiments 1 and 2.
These results show that experiment 2 was conducted at aA. lower temperature than experiment 1 and the reaction is endothermic.B. lower temperature than experiment 1 and the reaction is exothermic.C. higher temperature than experiment 1 and the reaction is endothermic.D. higher temperature than experiment 1 and the reaction is exothermic.
7 2007 CHEM EXAM 1
SECTION A � continuedTURN OVER
Questions 15 and 16 refer to the following information.One litre of an aqueous solution of potassium hydroxide (KOH) has a pH of 12.0 at 25°C.
Question 15The amount of solid KOH, in mol, that must be added to the solution to raise the pH to 13.0 would beA. 10�13
B. 10�12
C. 0.09D. 0.10
Question 16The amount of pure HCl gas, in mol, that must be added to the solution to lower the pH from pH 12.0 to 2.0 would beA. 10B. 2.0C. 0.02D. 0.01
Question 17Two bottles, I and II, have the same volume and are at the same temperature.Bottle I contains 10 g of argon gas only.Bottle II contains 10 g of neon gas only.Compared to bottle I, the number of atoms and pressure in bottle II would be number of atoms pressure A. equal the same B. equal higherC. approximately double the sameD. approximately double higher
Question 18A sodium lamp emits yellow-coloured light. If the light from the lamp was passed through a container of sodium vapour, it is likely that the light emerging from the container would appearA. brighter, due to electrons in atoms in the sodium vapour moving from higher to lower energy levels.B. brighter, due to electrons in atoms in the sodium vapour moving from lower to higher energy levels.C. duller, due to electrons in atoms in the sodium vapour moving from higher to lower energy levels.D. duller, due to electrons in atoms in the sodium vapour moving from lower to higher energy levels.
2007 CHEM EXAM 1 8
Question 19The reaction
A + B → C; ∆H negativeinvolves a two-step process
A + B → X; ∆H positiveX → C; ∆H negative
Which one of the following diagrams best represents the energy changes during the course of the reaction?
Question 20The following structure represents the repeating unit of a polymer used in the manufacture of contact lenses.
Which one of the following is a correct statement about the monomers that react to form this polymer?A. Each monomer contains a double bond between carbon atoms which allows addition polymerisation to
take place.B. Two different monomers react to form the polymer, one with carboxyl groups and the other with hydroxy
groups.C. The total mass of the monomers is greater than the mass of the polymer formed because water is eliminated
in the polymerisation reaction.D. Each monomer contains both a carboxyl and a hydroxy group which allows condensation polymerisation
to take place, forming a polyester.
course of reaction
energyA.
A + B
X
C
course of reaction
energyB.
A + BX
C
course of reaction
energyC.
A + B XC
course of reaction
energyD.
A + BX
C
CH3
CH2 C
C O
n
O
CH2
CH2OH
END OF SECTION A
9 2007 CHEM EXAM 1
This page is blank
TURN OVER
2007 CHEM EXAM 1 10
Question 1Carbon monoxide and hydrogen can be produced from the reaction of methane with steam according to the equation
Some methane and steam are placed in a closed container and allowed to react at a Þ xed temperature. The following graph shows the change in concentration of methane and carbon monoxide as the reaction progresses.
a. i. On the graph above, draw a line to show the change in concentration of hydrogen gas as the reaction progresses. Label this line.
ii. On the graph above, draw a line to show how the formation of carbon monoxide would differ over time in the presence of a catalyst. Label this line.
1 + 1 = 2 marks
SECTION B � Short answer questions
Instructions for Section BAnswer all questions in the spaces provided.To obtain full marks for your responses you should� give simpliÞ ed answers with an appropriate number of signiÞ cant Þ gures to all numerical questions;
unsimpliÞ ed answers will not be given full marks.� show all working in your answers to numerical questions. No credit will be given for an incorrect
answer unless it is accompanied by details of the working.� make sure chemical equations are balanced and that the formulas for individual substances include an
indication of state; for example, H2(g); NaCl(s)
concentration
time
CH4(g)
CO(g)
SECTION B � Question 1 � continued
11 2007 CHEM EXAM 1
SECTION B � continuedTURN OVER
b. Great care must be taken when handling carbon monoxide as it is a highly poisonous gas. Even at low concentrations it competes very successfully with oxygen for haemoglobin, the oxygen carrier in the blood.
What does the above information indicate about the magnitude of the equilibrium constant K1 compared with the magnitude of the equilibrium constant K2?
1 mark
c. The rates of chemical reactions may be explained using the collision theory model. Indicate whether the following statements about rates and the collision theory model are true or false by placing ticks in the appropriate boxes.
Statement True False
i. Endothermic reactions are always slower than exothermic reactions.
ii. All particles have the same kinetic energy at a Þ xed temperature.
iii. Reactant particles need to collide with sufÞ cient energy to react.
iv. The rate of a reaction at a constant temperature increases as the reaction proceeds.
v. Increasing the temperature increases the fraction of collisions with energy above the activation energy.
3 marks
Total 6 marks
2007 CHEM EXAM 1 12
SECTION B � continued
Question 2Bromophenol blue is a weak acid (represented as BH) that acts as an acid-base indicator. In solution the following equilibrium is established.
BH(aq) B�(aq) + H+(aq); Ka = 6.3 × 10�5 Myellow blue
At low pH bromophenol blue exists mainly as the acid, BH, which is yellow in colour, while at high pH it exists mainly as its conjugate base, B�, which is blue. An intermediate colour is observed when the concentration of the acid and the concentration of the conjugate base are similar.a. Write an expression for Ka in terms of the concentrations of BH, B� and H+.
1 mark
b. i. When [BH] = [B�], the mixture appears green. Calculate the pH at which [BH] = [B�].
ii. Calculate the ratio [B�]/[BH] when the pH of a solution of bromophenol blue is 7.
iii. What colour will the indicator solution appear at pH 7? Justify your answer.
2 + 1 + 1 = 4 marks
Total 5 marks
13 2007 CHEM EXAM 1
SECTION B � continuedTURN OVER
Question 3Some rocks were thought to consist of insoluble silica (SiO2) and calcium carbonate (CaCO3; molar mass 100.1 g mol�1). The fraction of CaCO3 in an 8.64 g sample of the crushed rock was determined by mixing the sample with excess hydrochloric acid. The acid reacts with CaCO3 according to the following equation.
2HCl(aq) + CaCO3(s) → CaCl2(aq) + H2O(l) + CO2(g)
The resulting solution was Þ ltered and the SiO 2 that was collected was washed and dried. The mass of SiO 2 was found to be 1.55 g. a. Calculate the expected percentage of CaCO3 in the original rock sample.
2 marks
b. In order to check the result from part a., excess ammonium oxalate solution was added to the Þ ltered solution. The calcium ions present precipitate as CaC2O4.H2O.
The CaC2O4.H2O was collected by Þ ltration, washed and dried. It was then heated to convert it to CaO (molar mass 56.1 g mol�1) and a mass of 3.87 g was obtained.
Using this mass of CaO, calculate the percentage of CaCO3 in the rock sample. Ensure that you express your answer to an appropriate number of signiÞ cant Þ gures.
3 marks
c. Suppose that the percentage of CaCO3 determined by the chemical analysis with ammonium oxalate was less than the result found in part a. above. Provide one possible explanation for the difference.
1 mark
Total 6 marks
2007 CHEM EXAM 1 14
Question 4Sulfur dioxide (SO2) is a chemical of major industrial signiÞ cance.a. SO2 gas can be produced in a reaction between concentrated sulfuric acid and nickel metal. A solution
containing Ni2+ ions is also formed. Write balanced equations for the i. oxidation reaction
ii. reduction reaction
iii. overall reaction, showing the states of all reactants and products.
1 + 1 + 2 = 4 marks
b. SO2 can also be produced in a chemical reaction between zinc sulÞ te (ZnSO3) and hydrochloric acid according to the equation
ZnSO3(s) + 2H+(aq) → Zn2+(aq) + SO2(g) + H2O(l)
Is this reaction also a redox reaction? Explain your answer.
1 mark
c. The SO2 produced as a by-product of the extraction of lead from its ore can cause serious pollution. In order to avoid releasing the SO2 into the atmosphere it is often collected and used to produce chemicals of industrial importance. Give the formula of such a chemical.
1 mark
SECTION B � Question 4 � continued
15 2007 CHEM EXAM 1
SECTION B � continuedTURN OVER
d. The following pairs of statements refer to the reaction of SO2(g) with O2(g) in the presence of vanadium (V) oxide. Each statement contains one or more missing words.
Circle the most appropriate words beside each statement. i.
Statements Circle the most appropriate words
1. The product of this reaction is _____________. oleum sulfuric acid sulfur trioxide
2. At constant temperature, the chemical energy of the product is ___________ the chemical energy of the reactants.
equal to more than less than
ii.
1. The equilibrium yield of product is _____________ as temperature decreases at constant pressure.
unchanged increased decreased
2. The equilibrium yield of product is _____________ as pressure increases at constant temperature.
unchanged increased decreased
iii.
1. The reaction rate is _____________ as the temperature increases at constant pressure.
unchanged increased decreased
2. The activation energy of the reaction is _____________ by the presence of vanadium (V) oxide.
unchanged increased decreased
1 + 1 + 1 = 3 marks
Total 9 marks
2007 CHEM EXAM 1 16
Question 5ParafÞ n oil contains a mixture of high molecular mass alkanes. A gaseous mixture of ethene and other low molecular mass alkanes and alkenes can be produced in the laboratory by heating parafÞ n oil in the presence of alumina.a. i. What is the general name given to this process?
ii. Suggest the likely function of the alumina.
1 + 1 = 2 marks
b. If one of the components of parafÞ n oil is C17H36, write a balanced equation in which this component forms ethene and only one other product.
1 mark
c. A chemist collects three samples of ethene and performs the following reactions. Write balanced equations for each one.
i. addition of bromine (Br2)
ii. complete combustion
iii. heated with steam and a catalyst at 300°C
1 + 1 + 1 = 3 marks
SECTION B � Question 5 � continued
17 2007 CHEM EXAM 1
SECTION B � continuedTURN OVER
d. A low molecular mass alkane was extracted from a gas sample obtained by this method. The following sequence of chemical reactions was then performed using this alkane.� The alkane was allowed to react with chlorine in the presence of ultraviolet light. Two compounds,
A and B, were formed, each of molar mass 78.5 g mol�1.� One of these two compounds was isolated and allowed to react with potassium hydroxide solution. The
product of this reaction was heated with acidiÞ ed potassium dichromate solution to form C, an acidic compound.
i. Draw the structural formulas of compounds A and B in the boxes below, showing all bonds present in the molecules. Give the systematic name of each compound.
Name ___________________________ Name ___________________________
ii. Draw the structural formula of compound C in the box below, showing all bonds present in the molecule. Give the systematic name of the compound.
Name ___________________________
4 + 2 = 6 marks
Total 12 marks
2007 CHEM EXAM 1 18
Question 6When the substance CH3CHO (substance X) is dissolved in water it reacts to form an equilibrium mixture with CH 3CH(OH)2 (substance Y) according to the equation
X(aq) + H2O(l) Y(aq)
The concentration of X can be determined using UV-visible spectroscopy. X absorbs strongly at 290 nm. Y shows no absorption at this wavelength.In a particular experimental arrangement at 25°C, the relationship between absorbance at 290 nm and concentration of X is given by
Absorbance = 4.15 × [X]
In the experiment, 0.110 mol of X is dissolved rapidly in 1.00 L of water at 25°C. The absorbance of the solution changes as some of the X is converted to Y. The table below shows the change in absorbance over time (measured in seconds).
Absorbance 0.430 0.303 0.270 0.255 0.250 0.250
Time (s) 6.00 60.0 90.0 120 240 480
a. Calculate the concentration of X, in M, when the reaction reached equilibrium.
1 mark
b. Calculate the absorbance at the instant that X was dissolved in the water, before any reaction occurred.
1 mark
c. Calculate the percentage of the original 0.110 mol of X that has been converted into Y at equilibrium.
2 marks
SECTION B � Question 6 � continued
19 2007 CHEM EXAM 1
SECTION B � continuedTURN OVER
d. The average rate of a reaction can be determined by calculating the change in concentration of a reactant per second. Calculate the average rate, in M s�1, at which the concentration of X changed during the Þ rst 6.00 s of the reaction.
2 marks
Total 6 marks
2007 CHEM EXAM 1 20
Question 7Sulfur dioxide gas is commonly used as a preservative in wine. An important source of SO2 is solid sodium metabisulÞ te (Na2S2O5; molar mass 190 g mol�1). Na2S2O5 reacts readily with acid as follows.
ii. Calculate the amount, in mol, of I3� added to solution A.
SECTION B � Question 7� continued
21 2007 CHEM EXAM 1
iii. The excess I3� remaining in the solution is determined by titration with a standard solution of sodium
thiosulfate (Na 2S2O3). The equation for the reaction is
S 2O32�(aq) + I3
�(aq) + H2O(l) → 3I�(aq) + S2O42�(aq) + 2H+(aq)
14.70 mL of a 0.00850 M solution of Na 2S2O3 reacts exactly with all the I3� remaining in solution B.
Calculate the original concentration of SO2 in solution A.
2 + 1 + 3 = 6 marks
Total 9 marks
END OF QUESTION AND ANSWER BOOK
CHEMISTRY
Written examination 1
DATA SHEET
Directions to students
This data sheet is provided for your reference. Make sure that you remove this data sheet from the centrefold during reading time. Any writing, jottings, notes or drawings you make on this data sheet will not be considered in the marking. At the end of the examination, make sure that you do not leave the data sheet in the centrefold of the question and answer book. You may keep this data sheet.